Ahtable load save

Adds the ability to load and save an ahtable object in architecture-agnostic way (uses 64-bit values where there is ambiguity).

I sent an earlier version of this pull request to luikore, but since we're merging code bases, I thought it made the most sense to start work on the main repository.
This doesn't work on travis or on my linux machine. I think `#define __USE_BSD` before including endian.h will do the trick.